Abu Dawud Book 12, Hadith Number 2888.

Narated By al-Mughirah ibn Shu’bah : Qabisah ibn Dhuwayb said: A grandmother came to Abu Bakr asking him for her share of inheritance. He said: There is nothing prescribed for you in Allah’s Book, nor do I know anything for you in the Sunnah of the Prophet of Allah (PBUH) Go home till I question the people. He then questioned the people, and al-Mughirah ibn Shu’bah said: I had been present with the Apostle of Allah (PBUH) when he gave grandmother a sixth. Abu Bakr said: Is there anyone with you? Muhammad ibn Maslamah stood and said the same as al-Mughirah ibn Shu’bah had said. So Abu Bakr made it apply to her. Another grandmother came to Umar ibn al-Khattab asking him for her share of inheritance. He said: Nothing has been prescribed for you in Allah’s Book. The decision made before you was made for a grandmother other than you. I am not going to add in the shares of inheritance; but it is that sixth. If there are two of you, it is shared between you, but whichever of you is the only one left gets it all.